The Ugandan presidential Mi-72 helicopter carrying Mr Garang back from a meeting with President Yoweri Museveni at his ranch in Rwakitura crashed in mountains near Mr Garang's base in New Site, southern Sudan.

Six of his associates and the seven-member crew also died in the crash, which has been blamed on bad weather.

Mr Garang had ruled the disparate SPLM with an iron hand, and managed to keep it together through years of fighting.

The conflict in Sudan ended with the signing of a peace agreement in January and Mr Garang became vice-president in a new government of national unity.

Sudan's President Omar al-Bashir said he was confident the peace agreement would remain on course.